The present disclosure relates to a power transmission device including a transmission, a case housing the transmission, and a brake that has a plurality of frictional engaging plates and a piston for pressing the frictional engaging plates and is configured to non-rotatably hold any of rotation elements of the transmission stationary to the case.
As a power transmission device of this type in the related art, a known power transmission device includes a speed change mechanism having a brake of a multi-plate friction type that can non-rotatably hold a sun gear of a reduction planetary gear stationary to a transmission case, a counter drive gear to which power from the speed change mechanism is transmitted, and a center support fastened to the transmission case with a bolt and rotatably supporting a counter drive gear through a bearing (see, for example, Japanese Patent Application Publication No. 2002-349683). A brake drum constituting the brake of this power transmission device includes a radial flange extending radially inward from one end of the brake drum. The radial flange has internal teeth on an inner peripheral portion thereof. The brake drum is non-rotatably held stationary to the center support by fitting the internal teeth to projections formed on a wall surface of an outer peripheral portion of the center support.